Catalytic steam reforming of real tar under high-efficiency Ni/USY catalyst for H2 production

A series of Ni/USY catalysts were developed by incipient wetness impregnation and applied for catalytic steam reforming of coal tar in a two-stage reactor. The reforming conditions, including Ni loading amount (5-20 wt%) and reaction temperature (600-900 degrees C), were studied. It was found that Ni/USY catalyst showed a superior catalytic activity in terms of tar conversion (81.3%) and H-2 yield (87.2 mmol/g) when the Ni loading amount was 15 wt% (i.e. 15NiY) and reaction temperature was 800 degrees C. The performance of 15NiY in terms of tar conversion decreased slightly after 180 min of reaction and could be recovered easily. According to N-2 adsorption-desorption analysis, as-prepared catalysts exhibited excellent porosity and the special surface area was higher than 450 m(2)/g. Ascribed to the high porosity and special structure of Ni/USY, Ni nanoparticles with a size of 10-50 nm were well dispersed, which was observed by XRD and FE-SEM/EDS. H-2-TPR demonstrated the strong metal-support interation of Ni/USY catalysts. The XPS spectra demonstrated that the surface of Ni/USY catalysts were enriched with surface adsorbed oxygen species and the value of Ni-0/Ni2+ reached the highest for (NiY)-Ni-15, which facilitated the extent of reaction. In addition, a kinetic model was applied for calculation of apparent activation energy and pre-exponential factor, which were 57.6 kJ/mol and 8.76 x 10(3) m(3) kg(-1) (catalyst) h(-1), respectively, indicating the effectiveness of Ni/USY catalyst.